docs: def _update_state(self, response):
          """Update the state of the browser. Create a new state object, and
          append to or overwrite the browser's state history.
  
          :param requests.MockResponse: New response object
  
          """
          # Clear trailing states
          self._states = self._states[:self._cursor + 1]
  
          # Append new state
          state = RoboState(self, response)
          self._states.append(state)
          self._cursor += 1
  
          # Clear leading states
          if self._maxlen:
              decrement = len(self._states) - self._maxlen
              if decrement > 0:
                  self._states = self._states[decrement:]
                  self._cursor -= decrement